Leukocyte adhesion to cold-preserved rat endothelial cells: Role of actin disassembly and ICAM-1

Abstract

Leukocyte adhesion on reperfusion is a critical component of cold preservation injury, and involves increased intercellular adhesion molecule 1 (ICAM-1) expression on sinusoidal endothelial cells (SEC). This study determined whether ICAM-1 expression occurs during cold preservation and whether actin disassembly is necessary for ICAM-1 expression and leukocyte adhesion. ICAM-1 expression was measured in isolated rat SEC during 8 hours of cold preservation by immunofluorescence techniques. Leukocyte adhesion to cold-preserved SEC was measured in an assay using fluorescently labeled leukocytes. The calpain inhibitors N-acetyl-leu-leu-norleucinal/N-acetyl-leu-leu-methioninal and the actin stabilizer phalloidin were added in some studies to prevent actin disassembly. Cold-exposed SEC showed a rapid increase of surface ICAM-1 expression, reaching maximum values in 1 hour. Studies in permeabilized cells suggested that ICAM-1 moved from a perinuclear location to the cell surface. Actin stabilization had no effect on the time-dependent increase in ICAM-1 expression, but seemed to affect the distribution of ICAM-1 on the cell surface. Leukocyte adhesion to SEC correlated with ICAM-1 expression and was reduced to control levels by an anti-ICAM-1 antibody. Although actin stabilization did not reduce ICAM-1 expression, it did reduce leukocyte-SEC adhesion to control values. Increased ICAM-1 expression on cold-preserved SEC is a direct effect of cold. It is not related to actin disassembly, although it seems that actin disassembly affects the distribution of ICAM-1. Leukocyte adhesion to cold-preserved SEC requires both increased ICAM-1 and actin disassembly. Agents that inhibit actin disassembly can significantly decrease leukocyte adhesion regardless of increased ICAM-1 expression.